Curing neoprene



Patented Nov. 26, 1946 I g i I v UNITED STATES PATENT OFFICE CURING NEOPRENE Byron W. Bender, Cupsaw Lake, N. 1., assignor to United States Rubber Company, New York, N. Y., a corporation of New Jersey No Drawing. Application April 5, 1945,

Serial No. 586,817

2 Claims. (on, 260-92.?)

1 l 2 I This invention relates to improvements in cur- Y Tau I 1 ing neoprene (polychloroprene) Mill mixed polychloroprene I have found that the curing rate of neoprene may be increased by incorporating with it, prior A B to cure, a small amount of a 3,3,3,3'-tetraalkyla 1,1'-spirobisindane-5,5,6,6'-tetrol, as an accel- H erator of'the cure. It is used preferably in oon- Effiiifitfifi'if..XZ?F.. :i1:3:::::::::::::::::::::::: f3 f3 junction with a curing agent such as a metal ggeggggggggggggp 12 12 oxide, known for the purpose, e. g., zinc oxide, Wood rosin 5 5 magnesium oxide, marge, {t a stanzatafaeaammmeal 2 i My accelerator avoids the disadvantages of accelerators such as catechol, resorcinol, and hydro- Y Tests on presswured slabs quinone, which are water-soluble and cause undesirable discoloration of the polychloroprene A 3 stock.

An accelerator of the class above referred to Minutes 0mm Elongation Elongation may .be prepared by reacting 3 mols of acetone Tame break Tepsue break with 2 mols of catechol, and by a method such V i as stated by Baker 8: McGowan, Journal Chemi- 2 7 P 51.5,, f' 3 cal Society '(1938), pages 347-353. $3

The proportion of the accelerator may be varv tion, the parts being by weight:

ied; generally useful proportions, by weight t The faster rate of cure of compound B containing based on the weight of the neoprene, range from my accelerator is shown by t l w r elongation,

0.1% to2%. si niii hi e m The accelerator may be used for accelerating g y n8 Eh I odmus.

the cure of any form 01' polychloroprene, milled TAB!" n or reclaimed, in solution, or in dispersion. The Polychlomprene latex accelerator 'is particularly useful in latex prod- Wmmut Zinc Oxide] ucts (those derived directly from a dispersion containing the neoprene) in which a quick cure C D and high modulus are desired, e. g., latex The following examples illustrate the invenlo'rai solids i-.'-' -.per c6155: is

Tests on films With zinc oxide] 4 highest modulus stock, the use of both zinc omde and my accelerator is indicated. E F The test data show that the above tetrol is a 1 t T 571' d m m wflery effective eiclcelerator in both milled and latex Polychlmpme a 8K We 5 5 orms o polyc oroprene, As att of fact 11; iiifitfilttttfff? In it be use d win caution in milled stocks to I 5 avo d scorch me an precuring of the stock before tiinitiiifiiffiit. iffiiffifiiffi fiii23%;; 4 molding. In this respect, its action may be compared to that of the so called ultra accelerators Tests on films Modulus Modulus 5:33:2 Tensile 335 Tensile fio 300% 500% at break 300% 500% at break an a l60-F. P. 0.1. Percent 1 .0. i. Percent plus. 100 160 1,400 1,140 210 300 1,900 030 30at250 110 1230 2,300 1,030 280 380 2,600 730 so 250 330 2,500 820 380 400 2,500 640 1a) 300' 400 2,300 710 480 630 2,500 600 A" Dimethylamine oleate was added as 10% soluin rubber. Because of this tendency to scorch no milled stocks; it will be of the greatest value in Sodium alginate was added as 2% solution. polychloroprene latex, Just as the rubber ultra The test films were poured on glass plates and accelerators may be used more safely in latex air-dried 16 hours at 70 F., then heated for one than in milled stocks. hour at 160 F., then further cured by heating for Having thus described my invention, what I various periods at 250. F., as indicated. claim and desire to protect by Letters Patent ls: It may be seen from the above data for com- 1. A method of accelerating the cure of polypounds C and D that in the absence of zinc oxide chloroprene which comprises incorporating my accelerator has only a very slight efiect on therein, priorto cure, a small amount of 3,3,3',3- modulus and breaking elongations and films from tetramethyl-1,1'-spirobisindane-5,5,6,6-tetro1. both of these compounds have low modulus and 2. A method of accelerating the cure of polyhigh breaking elongation. However, in the presc o opre e w c co p e incorporating e ence of zinc oxide, the data for compounds E and prior o cure, a small amount of 3, 33 Show that my amelemtor has marked I tetramethyl-1,1'-spirobisindane 5,5',6,6' -tetrol,

celerating influence and causes appreciable rise and Zinc Oxidein modulus and decrease in breaking elongation BYRON W.'BENDER. for a given time of cure. Thus, to obtain the 40 

